Exhaled nitric oxide levels in non-allergic and allergic mono- or polysensitised children with asthma

Background-Increased fractional exhaled NO concentrations (FENO) and blood/ tissue eosinophilia are frequently reported in allergic children with mild asthma and are thought to reflect the intensity of the inflammation charact erising the disease. The aim of this study was to investigate possible diff erences in FENO levels or in the intensity of the blood eosinophilia in all ergic and non-allergic asthmatic children. Methods-112 children with stable, mild, intermittent asthma with a positive bronchial challenge to methacholine were consecutively enrolled in the stu dy; 56 were skin prick test and RAST negative (nonsensitised) while 56 were sensitised to house dust mites (23 only to house dust mites (monosensitise d) and 33 were sensitised to mites and at least another class of allergens (pollens, pet danders, or moulds)). Nineteen sex and age matched healthy ch ildren formed a control group. Results-Compared with non-allergic patients, allergic children had a signif icantly higher rate of blood eosinophilia (p=0.0001) with no differences be tween mono- and polysensitised individuals. Forced expiratory volume in 1 s econd (FEV1), forced vital capacity (FVC), forced expiratory flow at 25-75% of vital capacity (FEF25-75%), and the degree of bronchial reactivity to m ethacholine were similar in non-atopic and atopic children, with no differe nces between mono- and polysensitised individuals. FENO levels measured by chemiluminescence analyser were higher in asthmatic children (15.9 (14.3) p pb) than in the control group (7.6 (1.6) ppb, p=0.04) and higher in allergi c patients (23.9 (2.1) ppb) than in non-allergic patients (7.9 (0.8) ppb, p =0.0001), but there were no differences between mono- and polysensitised in dividuals (p >0.1). Significant correlations between blood eosinophilia and FENO levels were seen only in allergic (r=0.35, p <0.01) and in polysensit ised individuals (r=0.45, p <0.05). Conclusions-In children with mild asthma, a similar degree of functional di sease severity may be associated with a higher inflammatory component in al lergic than in non-allergic subjects.